1. Field of the Invention
The invention relates to bolt fasteners; and, more particularly, to self-retaining positive locking bolts for use in aircraft or the like.
2. Description of the Prior Art
It has been the general practice in the aircraft industry to use bolts with castellated nuts and cotter pins to prevent nuts from becoming loose due to the vibration of the aircraft. On several occasions, after maintenance inspections or after repairs have been made on an aircraft, there have been instances where the bolt was inserted through the numbers to be secured together, but for some reason or other, the nut had not been fully threaded onto the bolt.
It can readily be seen that such mistakes or oversights on the part of ground maintenance crews could quite possibly result in the loss of a pilot and an aircraft should the bolt slide free of the members thus disconnecting the control linkage. These problems are particularly serious in high vibration environments, such as in aircrafts. There is thus a need for securing devices wherein the locking elements of the bolt keep the same in place even if the cotter pin is left off or breaks off, or the nut is either left off or unthreads due to vibration.
One such device is shown in U.S. Pat. No. 3,180,390 to Ockert. However, in this device, it is released at the head and material must be removed in the grip area of the shaft in the manufacture thereof. This weakens the device and minimizes use of bolts in certain high load operations.
Another such bolt is shown in U.S. Pat. No. 3,712,356 to Petroshanoff. This bolt requires a spring biased detent to remove the nut from the bolt body. Such detent and spring therefore must be carefully and precisely machined to operate properly. Another such bolt is shown in U.S. Pat. No. 4,278,120 to Hart et al. The Hart et al. bolt requires precise machining of the dog 38, the slope 44 on dog 38, and the surface 32 on cam member 30.
There is a need for a self-retaining positive locking bolt which remains in place even if the cotter pin or bolt is left off or the pin breaks or the nut unthreads, does not require careful and precise machinery of parts to be removable from a work structure and can be made easily and inexpensively from conventional bar stock.